For decades, Southern California’s fight against smog has focused on strategies to reduce pollution from tailpipe and smokestacks. But new research suggests that one of the main sources of lung-aggravating smog may be right under our feet.
The Salton Sea air basin, located in the heart of the Colorado Desert about 160 miles east of San Diego, is one of the most polluted regions in the country. At least a quarter of the nitrogen oxides, a precursor to smog, are emitted from irrigated green spaces in the region, according to a study from the University of California, Davis.
From Coachella Valley polo fields to Imperial County farms, fertilizer and irrigation have transformed the vast, harsh Colorado desert into lush fields. Although these conditions are ideal for plants, the moist, fertile soil creates a feeding frenzy for soil bacteria that releases pollution that forms smog.
Researchers at the University of California, Davis found that soils in the Salton Sea Atmospheric Basin emit more than 11 tons of nitrogen oxides per day, about the amount currently estimated by California air quality regulators. It is said to be 10 times more smog-forming pollution. Ian Faruna, an associate professor in the Department of Land, Atmosphere, and Water at the University of California, Davis, said the study’s findings shed light on how farmland and well-maintained lawns contribute to local air quality. It emphasizes the need for a deeper understanding.
“Fertilizer is relatively cheap, so farmers typically apply about twice as much fertilizer as their crops need to ensure availability,” Faruna says. “So when you have a lot of excess nitrogen, microorganisms go to town and start using it as fuel. But some of it leaks out of your metabolism and comes out as air pollutants.”
In California, Imperial County ranks 9th in agricultural sales with $2 billion in revenue. But to grow crops like iceberg lettuce and broccoli in the low desert, farmers use more fertilizer than in any other county. Previous studies have shown that applying too much fertilizer is five times more likely to produce smog-forming nitrogen oxides.
Fertilizer sales in Imperial County have more than doubled since 1991, according to estimates from the California Department of Food and Agriculture.
To withstand extreme heat and dry conditions, crops in the Salton Sea-Air Basin require regular watering. But high temperatures and soil moisture can cause even more emissions.
When water is supplied to agricultural land, a “pulse event” can occur where soil bacteria reactivate and large amounts of pollutants are released.
These pollution spikes typically last one to two days, which may be why state air regulators have not previously considered soil emissions to be a significant source of pollution near the Salton Sea.
“We looked, but we probably didn’t look closely enough to capture these soils,” Faruna said. [pollution]”
In a region known for its vegetable cultivation, the findings highlight the need for greater transparency about current fertilizer application and irrigation practices, which are not currently tracked extensively by government agencies. There is.
“We don’t want to jeopardize food production, we just want to do it in a way that has the least negative impact on the environment,” Faruna said. “The more we learn about it, the more details will emerge about the best steps to take.”
Air pollution near the Salton Sea has been a long-standing concern for residents. In addition to unhealthy levels of smog during the summer, residents had to contend with polluted dust from the rapidly disappearing Salton Sea, California’s largest lake.
For decades, the Salton Sea has been the final destination for agricultural runoff containing toxic pesticides and fertilizers. As the lake shrinks, more of its bed continues to be exposed, and winds kick up toxic dust.
Daniela Flores, founder of the Imperial Valley Equity and Justice Coalition, said many parents are limiting their children’s time outside because of consistently poor air quality.
Still, Imperial County has one of the highest rates of asthma-related emergency room visits for children. Compounding the problem is that many of the region’s rural residents do not live near hospitals or medical facilities.
“I don’t think there’s an environmental disaster anywhere in California that mirrors the Salton Sea,” Flores said. “How sad is it that we live in communities where parents have to tell young children they can’t go outside and play because the weather is bad outside?”
For Flores, the UC Davis study confirms what many had suspected about the environmental damage and health impacts of the region’s agricultural industry.
“Allergies, asthma, missing school, it’s like a part of life,” she said. “People know it’s not right. People know it’s not normal. In many ways, I feel like people are feeling the effects of it. [pollution]And science comes a little later. ”
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